In 1987 Square put a trademark on the name 'Seiken Densetsu'. The english translation of this means 'Holy Sword Legend'. They where working on a project called 'The Emergence of Excalibur'. The game was under the guide of Kazuhiko Aoki. The game was being developed for the famicon disc system, and it was intended to be 5 discs long. Which at the time would have made it the largest game for a nintendo system.
Square thought the game was going to be very successful. They started allowing the game to be pre-ordered before they even began programming. However due to finacial problems and market failures square was facing bankrupcy and several projects had to be cancelled including 'Emergence of Excalibur'.
Fans received a letter from Square annoucing the games cancellation and giving them a refund for their pre-order. In this same letter Square detailed a new RPG they where developing which was called 'Final Fantasy'.
In 1990 Koichi Icchi, Yoshinori Kitase, and Goro ohashi began work on a new game boy adventure called Gamma nights.


The emergence of excalibur cancelled NES game

Rather than being a turn based RPG it would be an action RPG like Zelda. For the game Koichi Icchi was inspired by works such as Alice In Wonderland, lord of the rings and Moomin.
However Square wanted to add more to the game so they decide to incorporate elements from the scrapped project 'Emergence of Excalibur' into the game. When released in Japan the game was called Seiken Denesetsu Final Fantasy Gaiden. It was in fact the first title in the mana series.

When the game came to the US it was called Final Fantasy Adventure simply to give it stronger branding. As Final Fantasy was Square's most successful brand in the US at that time.
Final Fantasy Adventure was the first game in which US players encountered Chocobos and Mogul. The game released in the US on November 1st, 22 days before the release of Final Fantasy 2 which came out on November 23rd in the US.